Osmosis And Diffusion Lab Report

Cells and molecules in the environment are constantly moving and changing, for cells to function properly there is a need for equilibrium to be met. The size of the cell and the solution outside of the cell affects the rate of diffusion and osmosis in the cell. Cells are constantly trying to reach an equilibrium with the molecules and substances around it, which is why there are such terms as: hypertonic, hypotonic and isotonic. The procedures allowed testing of whether or not surface area or volume increased diffusion and how different substance control diffusion. Cells are constantly moving to reach equilibrium through diffusion and osmosis.

Explain what happened to the blood cells at the various levels of concentration. Be sure to refer to the solutions as being hypotonic, hypertonic and isotonic.

Osmosis is described in one of three ways when comparing more than one solution. The cell’s external and internal environment helps determine tonicity, which is defined as how the cell reacts to its environment. When the cell’s environment is equal in osmolarity to itself and there is no change, it is considered an isotonic solution. When the environment has a higher osmolarity, shrinkage occurs and it is considered a hypertonic solution. When the environment has a lower osmolarity, swellings occurs and it is considered hypotonic.

The purpose of these experiments is to examine the driving force behind the movement of substances across a selective or semiperpeable plasma membrane. Experiment simulations examine substances that move passively through a semipermeable membrane, and those that require active transport. Those that move passively through the membrane will do so in these simulations by facilitated diffusion and filtration. The plasma membrane’s structure is composed in such a way that it can discriminate as to which substances can pass into the cell. This enables nutrients to enter the cell, while keeping unwanted substances out. Active

A major determinant of diffusion in a biological system is membrane permeability. Small, uncharged molecules pass through cellular membranes easily, while most and/or charged molecules cannot pass through the membrane. The movement of water across a selectively permeable membrane, like the plasma membrane

The concentration of dissolved substances is greater in the extracellular fluid than in the cytoplasm. Hypertonic Solution Concentration of dissolved substances (solute) Concentration of water (solvent) What happens to an animal cells? Inside the cell Less Greater Outside the cell Greater Less Membrane

The difference is that along with large molecules, living cells prevent molecules with positive charges and solubility. This is not representing in dialysis tubing, and is only found in living cells because the tubing is only based on molecular size (98). When referring the rate of diffusion, the concentration gradient influences the diffusion rate, based on the factors of temperature. The ability for molecules diffuse from high to low concentrations primarily depends on the concentration gradient between the two areas.(96-99). My hypothesis for the study is that in the hypotonic, hypertonic, and isotonic solutions, the direction and rate of osmosis will determine based on the concentration inside the dialysis tubing. My prediction is that if the solution is hypotonic the results will decrease, if the solution is hypertonic the results will increase and if the solution is isotonic the solution will vary and or remain constant.

The following hypothesis was made in regard to effect of the concentration gradient on the rate of diffusion: The higher the concentration gradient, the faster the rate of diffusion.

I.Problem: How are materials passed into and out of a cell? What environmental factors might influence the passage of said materials? II. Background: -Water is used as a medium of transport for other materials -A cell membrane is semipermeable ( allows only specific substances to enter) Passive transport: the movement of ions and other atomic or molecular substances across cell membranes without need of energy input.

The diffusion across a cell membrane is a process of passive and spontaneous net movement of small lipophilic molecules. The molecules move from a high concentration to a low concentrated region along the concentration gradient. The result being a point of equilibrium, this is where a random molecular motion continues but there is no longer any net movement. However, there are things that can affect the rate of diffusion, these being temperature, surface area, concentration, size of the molecule, permeability, diffusion distance and concentration difference. Osmosis is a type of diffusion as it is the movement of water molecules through a semipermeable membrane into a region of higher solute concentration. Equilibrium is reached when the solute concentration is equal on both sides. Water potential is measured in kiloPascals, it is the measuring of the concentration of free water molecules that are able to diffuse compared to pure water, which is 0 kilopascals. It is a measure of the tendency of free water molecules to diffuse from one place to another. The result being, the more free water molecules, the higher the Water Potential. However, Water potential is affected by two factors: pressure and the amount of solute.

Cells are always in motion, energy of motion known as kinetic energy. This kinetic energy causes the membranes in motion to bump into each other, causing the membranes to move in another direction – a direction from a higher concentration of the solution to a lower one. Membranes moving around leads to diffusion and osmosis. Diffusion is the random movement of molecules from an area of higher concentration to an area of lower concentration, until they are equally distributed (Mader & Windelspecht, 2012, p. 50). Cells have a plasma membrane that separates the internal cell from the exterior environment. The plasma membrane is selectively permeable which allows certain solvents to pass through

All cells contain membranes that are selectively permeable, allowing certain things to pass into and leave out of the cell. The process in which molecules of a substance move from an area of high concentration to areas of low concentration is called Diffusion. Whereas Osmosis is the process in which water crosses membranes from regions of high water concentration to areas with low water concentration. While molecules in diffusion move down a concentration gradient, molecules during osmosis both move down a concentration gradient as well as across it. Both diffusion, and osmosis are types of passive transport, which do not require help.

Hypertonic is what the side with a higher concentration of solutes is called. Hypotonic is the side with a lower concentration of solutes. In osmosis the water moves to the hypertonic side from the hypotonic side.

So for example, if there’s 10% of salt outside the cell and 20% inside the cell, the water molecules would move into the cell to make the solute concentration proportional and equal. A hypertonic solution is one with higher solute concentration than a cell, which results in a decrease in size. So for example, if there’s 20% of salt outside the cell and 10% salt inside the cell, the water molecules would move out of the cell to make the outside of the cell proportionate to the inside. It is like the opposite of a hypotonic solution. An isotonic solution is a solution with the same solute concentration as a cell.

In a hypotonic solution, the inside of the cell has a higher concentration of solute than the outside of the cell. This causes more water to enter the cell than leave the cell, meaning a positive net movement of water into the cell. Because of this, the cell swells and becomes larger due to the intake of water. In a hypertonic solution, the inside of the cell has a lower concentration of solute than the outside of the cell. This means that water leaves the cell, making for a negative net movement of water into the cell.